Vacuum type circuit interrupter device



Aug. 9, 1966 VACUUM TYPE CIRCUIT INTERRUPTER DEVICE E. L. LUEHRING FiledDec. 12, 1963 FIGZ INVENTOR ELMER LUEHRING ATTORNEY United States Patent"ice 3,265,840 VACUUM TYPE CIRCUIT [NTERRUPTER DEVICE Elmer L. Luehring,Cleveland Heights, Ohio, assignor t0 Joslyn Mfg. and Supply Co.,Chicago, 111., a corporation of Illinois Filed Dec. 12, 1963, Ser. No.330,125 5 Claims. (Cl. 200-124) This invention relates to circuitinterrupters and has particular significance in connection with contactoperating structure in a vacuum, or other enclosed against ambient,switch.

In high voltage power line switching and disconnect apparatus,interrupter contacts which, for opening sequence (see, for example H 12,US. Pat. 2,955,181, Luehring, assigned to the assignee of the presentinvention) break a circuit in a vacuum, or in an inert gas such as SPhave become well known and widely accepted. The enclosed against ambientinterrupter is expensive and a large economic loss results whensurrounding parts, oil, etc., are affected by catastrophic failure ifthe enclosed contacts attempt to, but are in fact unable to, open a rcircuit, e.g., because abnormal high current or other conditionsprevail.

It is an object of the present invention to provide simple means forovercoming the above mentioned difficulty.

Other objects and advantages will become apparent and the presentinvention may be better understood from consideration of the followingdescription taken inconnection with the accompanying drawing, in which:

FIG. 1 is a sectional view of a vacuum switch incorporating stationaryand movable contact structure according to the invention; and

FIG. 2 is an enlarged view showing a modification for the movablecontact support structure.

Referring first to FIG. 1, an evacuated envelope 10 of an insulatingmaterial such as glass is provided with suitable conventional seals torender the envelope vacuum tight. As illustrated, the envelope enclosesan upper fixed contact 11 and a lower movable contact 12. Contact 11 isconnected by a rod 13 to a terminal 15 which is also fixedly stationary.

The movable contact 12 has a depending portion 16 (e.g., of copper)which is initially loosely mounted in a tubing 18 of conductive materialsuch as copper. Tubing 18 is electrically associated with a terminalconductor 20 and mechanically associated, as through a pin 22 and an endfitting 24, with an insulating material control rod 26 which, due tooperation of conventional apparatus (not shown), normally pushes uponthe movable contact to close and pulls upon it to open the contacts. Aconventional flexible metallic bellows 28 seals parts associated withenvelope with respect to parts associated with movable contact, and acompression spring 30 biases movable contact portion 16 upwardly for apurpose later to be explained.

The contact 12 and the contact portion 16 are bonded together in a hightemperature resisting joint, or are integrally fashioned as one piece,while the contact portion 16 and the portion of the rod 18 thereaboutare normally held together by a braze or relatively low temperaturejoint, e.g., with -a eutectic alloy solder 32 or by a silver solder, inany even having a melting point lower than that of the contact 12, theportion 16 and the tube 18.

In the modification shown in FIG. 2 the contact 12 depending portion isdivided into a top (soldered) piece 16a which may be of copper and abottom thermal insulator piece 16b which may conveniently be of alumina(A1 0 16a and 16b are held in mutual engagement by the spring 30 and inFIG. 2 a pin 34 is shown serving as a restrainer for the opposite end ofthe spring.

Patented August 9, 1966 In designing apparatus according to theinvention the solder length dimension L (see FIG. 2) is preferably madegreater than the full open position contact space S (see FIG. 1).

During operation, if (1) the contacts, upon opening, fail to interrupt acurrent flowing through them, (2) the heat from arcing causes the solder32 to melt whereupon (3) the spring 30 serves to reclose the contacts.With the are thus eliminated the heating of the parts is reduced and (4)the solder will resolidify, it being understood, of course, that forpurposes of clarity some of the dimensions in FIGS. 1 and 2 (not toscale) are exaggerated and normally the solder layer will be thin enoughso that the liquid solder of step 3, though it serves as a lubricant,will be held in place by capillary action.

Steps 1, 2, 3 and 4 all occurred during the contact opening sequence (ofrod 26 operation), but after step 4 (contacts closed) the switch willresist any subsequent efforts of closure and thereby warn a humanoperator of a failure which is, however, relatively inexpensive to cure.

Normally the switch failure (failure to interrupt) will be due to lossof vacuum or ambient gas, oil or whatever. To protect against a switchfailure due to any other cause the .solder 32 can be placed off-center(that is thicker at one side of tube 18 than at another) so that withloss of vacuum or insulating fluid, and consequent melting of solder,only the solder at the thicker solder side will be displaced by anypressure differential, while at the sides where the solder layer isthinner some molten solder will remain in place, by capillary action, sothat the latter can resolidify (with cooling) and hold in closedposition the switch which has failed.

There is thus provided arrangements of the class described capable ofmeeting the objects above referred to and of protecting a vacuum, or gasambient, or even an air switch of proper design, against catastrophicfailure, contact burn out, explosions, and the like, by causing thecontacts to close automatically (and stay closed) if overheated becauseunable to interrupt a circuit current.

While I have illustrated and described particular embodiments, variousmodifications may obviously be made without departing from the truespirit and scope of the invention which I intend to have defined only bythe accompanying claims taken with all reasonable equivalents.

Iclaim: 1. A vacuum type enclosed electric circuit interrupter having:

a housing, first and second terminals, I a stationary contactelectrically connected to said first terminal and mounted within, andstationary with respect to, said housing, a movable contact mountedwithin said housing and electrically connected to said second terminal,means including a control rod portion and operating temperatureresponsive solder connecting said control rod portion to said movablecontact for normally alternately moving said movable contact intoengagement with and away from said stationary contact, and meansincluding a spring having one end connected to said control rod portionand an opposite end connected with said movable contact for biasing saidmovable contact away from said control rod portion thus biasing thecontacts together during an abnormal condition such that saidtemperature responsive solder is ineffective to operate said movablecontact. 2. In an enclosed high voltage interrupter switch, thecombination comprising:

a housing having a pair of terminals,

a stationary contact supported by and within said housing and connectedin circuit with one of said terminals,

a contact normally movable within said housing and adapted to cooperatewith said stationary contact and connected in circuit with the other ofsaid terminals,

a conductive material extension of said movable contact,

a control rod means normally connected to said conductive materialextension and for normally operating the movable contact to open andclosed positions, with respect to the stationary contact, where the openposition represents a contact spacing of S, said control rod meanshaving a portion connected by relatively low melting point solder tosaid conductive material extension over a length L when said solder isin its first in situ solid state, and

a spring means having one end connected to said control rod means andits other end connected to operate said conductive material extension ofsaid movable contact and for biasing said conductive material extensionaway from said control rod means, whereby said movable contact is heldin engagement extension and for preventing heat drain from saidextension to said spring means.

5. A high voltage electric circuit interrupter having first and secondnormally engageabl'e and disengageable contacts,

first retaining means connected to retain said first contact,

second retaining means connected to normally retain said second contact,

said second retaining means comprising an operating temperatureresponsive solder joint,

a spring having one end connected to said second contact and its otherend connected to a portion of said second retaining means whereby saidspring, during operation, whenever, and after, the solder has meltedbiases said contacts substantially permanently together, and

control rod means connected through one of said re-' taining means tothe associate one of said contacts and for, before the solder hasmelted, normally selectively disengaging and engaging said contacts. 9

References Cited by the Examiner UNITED STATES PATENTS by the length Lbeing greater than the spacing S.

' by, a member of thermal insulating material interposed with saidstationary contact, at any time when, and 2,472,625 6/1949 Smith 200-144after, the solder subsequently reaches a liquid state, 2,934,628 4/ 1950Massar et a1 200-418 despite sequence of control rod operation,3,179,770 4/1965 Demaret 200-1 18 3. The combination of claim 2 furthercharacterized 3,18 5/ 1965 Lee et 4. The combination of claim 2 furthercharacterized BERNARD GILHEANY, Examiner- H. B. GILSON, AssistantExaminer. between said spring means and said conductive material

5. A HIGH VOLTAGE ELECTRIC CIRCUIT INTERRUPTER HAVING FIRST AND SECONDNORMALLY ENGAGEABLE AND DISENGAGEABLE CONTACTS, FIRST RETAINING MEANSCONNECTED TO RETAIN SAID FIRST CONTACT, SECOND RETAINING MEANS CONNECTEDTO NORMALLY RETAIN SAID SECOND CONTACT, SAID SECOND RETAINING MEANSCOMPRISING AN OPERATING TEMPERATURE RESPONSIVE SOLDER JOINT, A SPRINGHAVING ONE END CONNECTED TO SAID SECOND CONTACT AND ITS OTHER ENDCONNECTED TO A PORTION OF SAID SECOND RETAINING MEANS WHEREBY SAIDSPRING, DURING OPERATION, WHENEVER, AND AFTER, THE SOLDER HAS MELTEDBIASES SAID CONTACTS SUBSTANTIALLY PERMANENTLY TOGETHER, AND CONTROL RODMEANS CONNECTED THROUGH ONE OF SAID RETAINING MEANS TO THE ASSOCIATE ONEOF SAID CONTACTS AND FOR, BEFORE THE SOLDER HAS MELTED, NORMALLYSELECTIVELY DISENGAGING AND ENGAGING SAID CONTACTS.